JP2000180667A - V-groove adaptor for mutually connecting photoconductor and manufacture of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive connector for mutually connecting the photoconductors of different sizes with correct alignment of their centers by comprising two axially aligned V-grooves having predetermined sizes different from one another. SOLUTION: A V-groove adaptor 20 comprises a large V-groove 22 and an adjacent small V-groove 24. The large V-groove 22 and the small V-groove 24 are arranged close to one another while longitudinally aligned along a common central axis 25. The large V-groove 22 and the small V-groove 24 are connected to one another in a structural member 26, whereby they form a cross section 28. The large V-groove 22 is defined by a reference cut surface 30 and a bottom surface 32 opposite to one another. The large V-groove 22 supports a first photoconductor inside thereof. Similarly the small V-groove 24 is defined by the opposite reference cut surface 36 and supports a second photoconductor inside thereof. The V-groove adaptor 20 can be massproduced by using the injection molding technique, and can be manufactured with high accuracy at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention generally relates to an optical fiber,
In particular, it relates to the interconnection of two light guides.

[0002]

BACKGROUND OF THE INVENTION Fiber optic networks are ever-increasing, partly due to the large bandwidth provided by fiber optic cables. The design of any fiber optic network inherently requires that individual fibers be connected to other fibers and equipment. A common technique for connecting optical fibers is to terminate the optical fiber with a ferrule and connect the ferrule to another ferrule that terminates a second fiber. The ferrule receives two ferrules of similar size and is precisely aligned by a cylindrical sleeve that coaxially aligns the longitudinal axis of its individual core. The sleeve is typically a component of a coupler or adapter that securely couples the individual fiber optic plug housings. Examples of such connection systems can be found in U.S. Patent Nos. 4,738,507 and 4,738,508, both issued to Palmquist and assigned to the assignee of the present invention.

[0003] Recent advances have led to the design of smaller fiber optic connection systems and the use of smaller ferrule diameters. Smaller ferrules offer the advantage of being more balanced in size with fiber optic cables, having better axis alignment, and being more space efficient. In particular, relatively small connectors
It can be packed more densely on the surface of network equipment, and thus can manage space more efficiently.

[0004] A miniaturized connector design has a diameter of 1.25.
mm ferrule is used. One example of a miniaturized ferrule connector is an LC connector. Small ferrule
Prior to the development of connectors, most connectors used ferrules with a diameter of 2.5 mm, twice the ferrule diameter of small ferrule connectors. One example of a large ferrule connector is STTM (Lucent Techn.
Technologies, Inc.).

[0005]

The use of small ferrule connectors has many advantages, some of which have been described above, but which are compatible with many existing optical networks that use large ferrule connectors. There is a problem of sex.
Large ferrule connectors have been in use for many years and are widely used in optical networks. In most situations, replacing an existing fiber optic network with new fiber optics using miniature ferrule connectors is impractically expensive. Thus, when equipment or hardware is upgraded or installed in an existing optical network, new equipment or hardware is designed to use small ferrule connectors, and existing equipment or hardware uses large ferrule connectors When so designed, engineers face the problem of how to interconnect two optical terminations with ferrules of different sizes. Therefore, there is a need in the industry for an efficient and economical way of interconnecting two ferrules of different sizes in an optimal connection.

One proposed solution is to use a mixed cable having a large ferrule connector at one end and a small ferrule connector at the opposite end. While such a mixed cable is a relatively simple solution, it is rather cumbersome to use and requires two connections to connect two optical fibers (ie, additional connections). Add parts) and are relatively expensive. Yet another proposed solution is a step-sleeve adapter with a centrally-fitting cylindrical sleeve with coaxially aligned lumens of different sizes on both sides of the sleeve. Thus, approximately at the center of the step sleeve, the inside diameter of the sleeve defined by the lumen changes from a first inside diameter (corresponding to a small ferrule) to a second inside diameter (corresponding to a large ferrule). This design requires accurate sizing of the lumen and ferrule to ensure accurate and accurate alignment of the ferrule within the sleeve. In practice, such accuracy is not reproduced economically consistently. In addition, such step sleeves are usually
Made of a metal with a high coefficient of thermal expansion, the sleeve is therefore particularly sensitive to temperature changes. The step sleeve can alternatively be made of a ceramic material, but the ceramic sleeve is expensive to manufacture.

[0007] Accordingly, the industry has not realized a low cost connector for interconnecting light guides of different sizes by the precise alignment of their individual cores.

[0008]

SUMMARY OF THE INVENTION The present invention provides a V-groove adapter for interconnecting light guides of different sizes. In the present disclosure, a light guide defines an optical fiber therein,
For example, it may be a connector / ferrule finished by polishing or a composite structure composed of only optical fibers, but is not limited thereto. Further, different sizes of two light guides in this specification refer to the outer diameter of each light guide. A V-groove adapter according to the present invention is adapted to receive individual light guides and to provide two axially aligned V of different predetermined dimensions (eg, width and depth).
Grooves can be provided and the light guides are of different sizes.
The V-groove is a part of the alignment member, and holds two cores supporting the two light guides in a predetermined alignment relationship, such that the individual cores of the light guides are axially aligned such that they are coaxially aligned. Precise alignment is advantageous because the splice loss between the two optical fibers is reduced.

[0009] The V-groove adapter according to the present invention can be mass-produced using injection molding techniques, which are well known and relatively low cost. The mold used for injection molding is manufactured from a master V-block made of a monocrystalline material such as silicon, which uses masking and etching techniques commonly used in processing and manufacturing microelectronic devices. Manufactured in advance.
These techniques produce very accurate mechanisms and can be precisely controlled to tight dimensions. Therefore, V formed by using the injection mold formed according to the present invention.
Groove adapters can be manufactured inexpensively with a high degree of precision.

In accordance with one aspect of the present invention, a fiber optic adapter for aligning a light guide includes a first V-groove defining a first V-groove adapted to support a first light guide including a first central axis. The alignment member and the first V-groove are substantially axially aligned,
A second alignment member defining a second V-groove adapted to internally support a second light guide having a second central axis, the first and second V-grooves comprising a first and a second central axis. Are constructed to support the first and second light guides in a coupling relationship that aligns them in a predetermined manner. The diameters of the first and second light guides may be different, wherein the first V-groove and the second V-groove are:
It may have different dimensions (e.g., width and depth) as needed to provide a predetermined alignment. The predetermined alignment may include a coaxial alignment of the central axis or an offset alignment of the central axis.

The width of the V-groove defines the height of the center of the light guide supported in the V-groove with respect to the upper surface of the V-groove for a light guide having an arbitrary diameter. Therefore, the width of the V-groove is such that the V-groove is aligned with the central axis of the light guide (at the top of the V-groove).
The central axis of the light guide can be designed to be coaxially aligned with or offset axis aligned with the central axis of the V-groove. If desired, the V-groove can have a trough or truncated cross-section to maintain the structural portion of the connector below the V-groove and to regenerate the overall depth of the V-groove adapter.

According to another aspect of the invention, an optical fiber
A method of creating a connector mold includes creating a first V-groove of a first width and a second V-groove of a second width in a single crystal material, wherein the first V-groove and the second V-groove are defined with respect to each other. In alignment. The resulting structure is referred to herein as a master V-block. The metal is deposited in the aligned first and second V-grooves, and then the single crystal material is removed and the concave first and second V-groove recesses are drawn.
ve impression). next,
A metal member is used as a mold part for making a V-groove adapter.

A method for making a fiber optic adapter is as follows:
Providing a mold that defines the concave engraving of the first V-groove and the second V-groove, wherein the first and second V-grooves are positioned adjacent to each other and in a predetermined alignment with respect to each other. The mold is then used to form a fiber optic adapter having aligned third and fourth V-grooves, each of the third and fourth V-grooves having a predetermined axial alignment of the individual light guides. Thus, the light guide is supported inside.

The predetermined alignment of the light guide may be a coaxial alignment or an offset alignment as desired. Thus, two light guides having different outer diameters can be interconnected using a V-groove adapter. The V-groove adapter can be manufactured using injection molding techniques so that the V-groove adapter can be mass-produced. Preferably, the V-groove adapter comprises a plastic material. To account for plastic shrinkage during the injection molding process, the first and second V-grooves in the mold are:
It may be made slightly larger than the third and fourth V-grooves of the resulting adapter.

According to another aspect of the invention, an optical attenuator comprises:
A first alignment member defining a first V-shaped groove having a first width;
The V-groove is adapted to support a first light guide therein, and further comprises a second member defining a second V-groove of a second width, wherein the second V-groove supports the second light guide. Has become. The first and second V-grooves are constructed to support the first and second light guides axially aligned with a slight offset with respect to each other. The axial offset may be lateral or vertical or both, and is precisely controlled to cause a predetermined loss in the optical signal passing from the light emitting light guide to the receiving light guide. By precisely controlling the width of the first and second V-grooves, light guides of the same or different diameters can be interconnected with an optical attenuator according to the present invention.

According to yet another aspect of the invention, an optical fiber adapter for establishing an offset launch condition of an optical signal from a single mode fiber to a multimode fiber comprises a first V-groove defining a first width. 1V
The groove internally supports a light guide having a multi-mode core, and further includes a second V-groove of a second width, wherein a second alignment member defining the second V-groove includes a second light guide having a single-mode core therein. I have come to support it. The first V-groove and the second V-groove are axially offset from each other by a predetermined amount, thus
The optical signal input from the single mode core to the multimode core does not sufficiently fill the optical mode of the multimode core. The axial offset may be lateral, vertical, or in between.

[0017] Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. Such features and advantages are intended to be included herein within the scope of the invention, which is defined by the following claims.

The present invention can be better understood with reference to the following drawings. The elements of the drawing are
It is not necessarily to scale, emphasizing that the principles of the invention are clearly illustrated. Further, like reference numbers designate corresponding parts throughout the several views.

[0019]

Next, the present invention will be described in more detail with reference to the accompanying drawings showing preferred embodiments of the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided so that this disclosure will be thorough and complete. And should be construed to fully convey the scope of the invention to those skilled in the art.

A V-groove adapter 20 for interconnecting different sized light guides according to an embodiment of the present invention is illustrated in FIGS. 1A and 1B. The V-groove adapter 20 operates separately to interconnect the two light guides, or the V-groove adapter 20 can be incorporated into a coupler of a fiber optic connection system as described in the Background section. it can. In such a connection system, the ends of optical fibers having different sized ferrules can be optically interconnected using a coupler with a V-groove adapter according to the invention instead of a cylindrical sleeve. In the present disclosure, a light guide may be any device suitable for transmitting an optical signal, such as an optical ferrule or optical fiber. Further, as used herein, different sizes refer to the outer diameter of the individual light guides.

The V-groove adapter 20 has a larger V-groove 22
And an adjacent smaller V-groove 24. The large V-groove 22 and the small V-groove 24 are arranged close to each other so as to be vertically aligned along a common central axis 25. The large V-groove 22 and the small V-groove 24 connect to each other at a structural member 26, thereby forming a cross section 28.
Structural member 26 can take any suitable shape, such as the U-shape shown, a circle (not shown) having a central lumen interconnecting the light guides. The large V-shaped groove 22 is defined by the reference facet face 30 and the bottom face 32 facing each other. Large V-groove 2
2 is adapted to internally support the first light guide, as described in further detail below. Similarly, the small V-groove 24
Is defined by opposing reference facets 36, which are adapted to internally support a second light conduit, as described in further detail below.

Referring to FIGS. 2A and 2B, the V-groove adapter 20 is shown in use, where the first light guide 4 is shown.
6 and the second light guide 48 are connected to the core 5 of the first optical adapter 46.
0 and the core 52 of the second optical adapter 48 are optically interconnected such that they are coaxially aligned. The first light guide 46 and the second light guide 48 are held in place by individual locking mechanisms 51, such as leaf springs, clamps, or cantilevered arms that are fixed to the structural member 26 and extend over the light guides. You. In particular, the fixing mechanism 51 presses the light guides 46, 48 against the reference facets 30, 36, respectively. Fixing mechanism 51
Is held in place by a detent 54 and a spring guide 56.

The V-groove adapter 20 is used to interconnect different sized optical ferrules, and if each ferrule is part of an optical fiber termination, the ferrule will have a plug
A load is applied in the axial direction by a spring mechanism or the like built into the housing, and the plug housing maintains contact between the planar end faces of each ferrule, and thus maintains optical communication. For example, small ferrules such as LC connectors
The axial load applied in the adapter is approximately one pound (454 g) of force and the axial load applied in a large ferrule connector such as an STTM connector is
About 2 pounds (908 g) of power. As a result, the larger STTM ferrule is pressed against the cross-section 40 (FIG. 1A), and the axial load on the smaller LC ferrule maintains contact between the end faces of the two ferrules at the contact surface; The contact surface is transverse to the longitudinal axis of the individual ferrule.

A cross-sectional view of the interconnection between the first light guide 46 and the second light guide 48 is provided in FIG. Fixing mechanism 51
Are not shown to simplify the figure. According to the present invention, the wicks 50, 52 are coaxially aligned by the V-groove adapter 20, so that the wicks 50, 52 have a common longitudinal axis 6.
Has zero. Current manufacturing technology, as described below,
A V-groove adapter capable of aligning the cores 50 and 52 with an accuracy within 1 μm can be produced. However, advances in manufacturing techniques and materials will provide ever higher degrees of accuracy. Nevertheless, aligning the cores within 1 μm is more than sufficient for many current applications.

FIG. 4 provides a right side view of the V-groove adapter shown in FIG. 2B. As shown, the wicks 50, 52 are coaxially aligned along a longitudinal axis 60. Precise alignment of the wicks 50, 52 is achieved by configuring the V-grooves 22, 24 to support the light guides 46, 48, respectively, so that their central axes are at a common predetermined height. . In the presented embodiment, the reference facets 30 provide two contact lines 62 that support the light guide 46 so that for any diameter of the light guide 46, the central axis of the light guide 46 is in place. (That is, the height within the V-groove adapter). Similarly, the reference facets 36 provide two contact lines 64 that support the light guide 48 so that for any diameter of the light guide 48, the central axis of the light guide 48 is the same as the central axis of the light guide 46 It is formed to be at a predetermined position. Therefore, when the V grooves 22 and 24 are aligned in the axial direction, the central axes of the light guides 22 and 24 are coaxially aligned.
Reference facets 3 of various shapes other than those presented here
It can be seen that 0, 36 can be used to define a V-groove that supports and aligns the central axes of the light guides 46, 48 in a desired manner.

Design and Manufacture The central axes of the light guides 46, 48 and thus the cores 50, 52
V-grooves 22, 2
4 is first made of a single crystal material such as silicon. V
Grooves 22, 24 can be precisely made of a single crystal material using well-known photolithographic masking and etching techniques. In particular, anisotropic etching of single-crystal materials proceeds essentially along the crystal plane, which can form precisely predictable features. For example, as in the embodiments herein, a V-groove made of (100) silicon may have α = 70.5 as shown in FIG. 5A.
The reference facets 30, 36 are generated at a fixed angle of 2 °. In particular, a properly masked (100) silicon substrate can be anisotropically etched to produce a reference facet at a fixed angle α. The resulting V
The grooves are separated by {111} planes as shown in FIG. 5B.
It is understood that the etching process can be stopped before the two reference facets come together. This results in a trough or truncated cross section as shown by the V-groove (FIG. 4).

As shown in FIG. 6, the height H of the center C of the light guide 70 above the upper surface 82 of the silicon substrate 84 can be defined by the following equation (1).

(Equation 1) Where R is the radius of the light guide 70 and W is the V
The width of the groove.

Thus, for any desired height H and known light guide radius R, the corresponding width at the top of the V-groove (ie, the top surface of the silicon substrate) is given by the above equation (1)
Can be easily obtained using Table 1 below shows the V-grooves (μ) for various given heights H (indicated in μm).
m). Here, as in the case where the LC connector and the STTM connector are interconnected, one light guide is composed of 1.
It has a diameter of 25 mm and the other light guide has a diameter of 2.5 mm.

[0029]

[Table 1]

FIG. 7 shows that the light guide 86 is defined by the reference facet 90 so that the longitudinal axis of the light guide 86 is coaxially aligned with the center axis of the V-groove 88 and is flush with the upper surface 91 of the silicon substrate 92. 5 shows an embodiment supported within a V-groove 88 that is shown.
The height H 'of the center C of the light guide 86 above the point of contact (or contact) 94 can be calculated using equation (2) below.

(Equation 2) Also, as shown in FIG. 7, the V-groove 88 does not form a complete V-shaped cross-section, but includes a bottom surface 96 that connects the reference facets 90. The V groove 88 is formed below the silicon substrate 92 below the V groove 88.
Not fully etched to maintain the structural portion of the V-groove adapter and reduce the overall size of the V-groove adapter. V
The V-groove is not completely formed, as long as the groove has enough depth to receive the light guide, since the V-groove only provides two contact lines in the reference facet. That is, the lower portion of the V-groove can be removed without any effect on the performance of the V-groove, and in fact can be smaller and more robust without the lower portion of the V-groove. The minimum depth D is approximately the radius R of the light guide minus the height of the center axis of the light guide above the top surface of the silicon substrate (or if the center axis of the light guide is below the top surface, It is a value obtained by adding an additional clearance amount, such as 50 μm, to the value obtained by adding the distance from the upper surface to the central axis of the light guide.

For a light guide of a given diameter D (ie, 2R, where R is its radius), the following equation (3)
And a maximum V-groove width Wmax to prevent the light guide from contacting the bottom surface 96, as provided in (4) and (4), and the light guide is supported by the reference facet 90 and the top surface 91
There is a minimum V-groove width Wmin that ensures that W does not appear on the surface.

(Equation 3) Equations (3) and (4) can be used to calculate the appropriate width of either the large V-groove 22 or the small V-groove 24 of the V-groove adapter 20 (FIGS. 1A, 1B, 2A and (See FIG. 2B).

Once the desired dimensions of the V-groove have been determined,
A groove adapter can be created. To make V-groove adapters at low cost, V-groove adapters can be mass-produced using injection molding techniques. However, the V-groove of the V-groove adapter must be made with high precision to accurately align the core of the light guide within acceptable tolerances. Next, as described below, a metal layer is formed on the V-groove to form an inverse replica of the V-groove used as an insert for injection molding. For a detailed study of the technology for creating plastic injection molds, see Plastics Engineering H
andbook of Society of Plastic Industry, Inc. '' (Mic
Edited by hael L. Barons, Van Norstrand ReinHold, New Yo
rk, 1991).

Referring to FIG. 8, master V block 1
02 can be made of a single crystal material using the above design considerations and formulas. For example, small V-groove 1
The silicon substrate 104 can be masked and etched to create a large V-groove 106 that aligns with the predetermined 08. The dimensions given in FIG.
mm interconnects a 2.5 mm light guide. V-grooves 106, 108 are formed by conventional photolithographic masking and etching as is well known.
It can be created in the silicon substrate 104 using a process. In particular, an etching resistant mask is placed on top surface 110 of silicon substrate 104 so as to define the window by masking widths W1 and W2 of V-grooves 106 and 108, respectively. Next, usually KOH or EDP
The silicon substrate 104 is anisotropically etched using an etchant to generate the V-grooves 106 and 108.
In a preferred fabrication technique using a two-level masking procedure, the first etching step etches the wider V-groove to a first depth. In the next etching step, the narrow and wide V-grooves are etched at the end of the second etching step so that both sized grooves achieve the desired width and depth dimensions. A more detailed description of a two-level masking and etching procedure is given in US Pat. No. 5,632,908 issued to Shahid and assigned to the assignee of the present invention, which is incorporated herein by reference in its entirety. Incorporated in Alternatively, to etch the V-groove 106 further deeply,
When the desired depth D1 is reached in the V-groove 108, the etching is stopped, and then an etching-resistant mask is placed in the V-groove 108 to prevent further etching, and only the groove 106 is exposed to a subsequent etching step. Therefore,
Without further etching the V-groove 108,
In a subsequent etching step, a further etching can be performed to obtain a desired depth D2. However, it is known that alternative techniques for obtaining different V-groove depths may be used. For example, July 30, 1998
And filed with the assignee of the present invention, and incorporated herein by reference in its entirety, entitled "Method of Making Aligned Grooves in an O.
Application No. 09 / entitled `` ptical Connector Support Member ''
Once the grooves 106, 108 have been sufficiently etched from the contact line on the reference facet to a certain depth, as described in 126294 (Attorney Docket No. Shahid 31), the etch
The mold used in the injection molding process can be accumulated to stop the process and increase the depth of the V-groove in subsequent processes.

Next, in order to form an inverse replica of the V-groove,
A metal layer is electroformed on the master V block on the V grooves 106 and 108. A suitable metal for such purpose is nickel (Ni). Next, the silicon mesa is removed or destroyed, for example, by etching in a KOH aqueous solution. Next, the metal layer is inserted into a mold that defines the remaining shape of the V-groove adapter 20. A detailed discussion of how to make an injection mold from a master silicon substrate can be found in U.S. Patent Nos. 5,388,174 and 5,603,870, both of which are assigned to the assignee of the present invention.

Next, a plastic V-groove adapter is mass-produced using an injection mold. However, plastics are known to shrink during the molding process. Thus, the V-grooves 106, 108 must be made slightly larger than intended for the final V-groove adapter 20 to accommodate the shrinkage of the plastic during the subsequent molding process. Silicon Mesa 1
It has been determined that the V-grooves 106 and 108 in 04 should be made larger by about 0.4 to 0.6% to cope with shrinkage of the plastic material. Plastic materials with relatively small shrinkage include polyphenylene sulfide (PPS),
There are polyetheramides or liquid crystal polymers.

Therefore, the width of the V-groove in the master V-block can be precisely controlled by the masking and etching techniques. A V-groove adapter manufactured in a mold made from a master V-block can precisely support two light guides of different sizes (e.g., 1.5 mm and 2.5 mm in diameter) and thus each individual V-groove And when pressed against the reference facet of the V-groove by its individual locking mechanism, the center of the light guide (ie the longitudinal axis)
However, the center of the core of the light guide is perfectly aligned.

V-groove attenuator When the cores of two optical fibers are connected by an optical fiber connection,
It is well known to those skilled in the art that offsets in the cores of the coupled optical fibers result in imperfect light transmission from the transmitting optical fiber to the receiving optical fiber. The amount of signal loss in such imperfect transmission is determined by various parameters, such as the relative diameters of the individual cores, but it is widely accepted that there is a relationship between the mating core and the insertion loss. ing. Therefore, loss due to core offset is undesirable, but if such loss can be controlled precisely, it can be used in various applications such as optical attenuators.

In the design of fiber optic communication networks, optical attenuators are used to reduce the power level of the optical signal, as is well known in the art. However, to date, there is no attenuator to the best of the applicant's knowledge that can accurately and reliably provide low levels on the order of less than 3 dB. Loss due to single mode fiber core offset has been documented in detail (D. Marcuse, Loss Analysis of Single-Mode Fiber Splices, BST
703-71 of C, 56, No. 5 (May-June 1977)
However, to the best of the applicant's knowledge, no device exists that can accurately and consistently control the amount of offset with the precision required to provide a given loss, preferably at a level of less than 3 dB. For example, to establish a 1 dB loss, the lateral offset must be about 2 μm for a single mode fiber. Devices that can provide such offsets accurately and consistently have not been previously sold.

However, a V-groove attenuator according to the present invention can be manufactured using the design and manufacturing techniques described above and provide an offset with an accuracy within about 1 μm. The V-groove attenuator is used to adjust the master V
To produce a preform of the block, it can first be designed and manufactured on a silicon substrate, so that the insertion of the light guide into the resulting V-groove attenuator causes its individual core to be offset by a predetermined distance. I do. The offset may be vertical, horizontal, or both. further,
The coupling light guides may be the same size or different sizes.

For example, referring to FIG. 9, a V-groove attenuator 120 according to the present invention comprises a relatively small light guide 122 having a core 124 and a relatively large light guide 1 having a core 128.
26 is optically interconnected. In the sectional view of FIG.
A vertical offset 130 of 24 and 128 is shown. Although the light guides 122, 126 differ in size, those skilled in the art will appreciate that light guides of the same size can also be interconnected with a predefined offset. Again, by predefining the offset, the reduction in power transmitted from one light guide to the other can be precisely controlled in a consistent and repeatable manner. As will be appreciated by those skilled in the art, the vertical offset of one light guide relative to the other light guide can be precisely controlled by controlling the relative height of one light guide relative to the other light guide. it can. As discussed above, the height of the light guide is defined by the width of the V-groove on the top surface of the master V-block.

Referring to FIG. 10, a top view of the V-groove attenuator 130 includes a lateral offset. Light guides 132 and 134 of similar size are provided with individual cores 138 and 140
Are coupled together at a predetermined offset 136 such that they are offset by a known distance. In this embodiment, the lateral offset is precisely controlled by offsetting the axes of the V-grooves 132, 134 by a desired offset 136. The axes of the V-grooves 132, 134 can be precisely controlled by the masking and etching techniques described above when forming the master V-block.

Accordingly, the present invention provides a V-groove attenuator having a vertical and / or lateral offset of a predetermined distance to precisely control the loss and thus the signal attenuation.

Offset Launch V-Groove Launching an optical signal from a single-mode fiber into a multimode fiber to partially fill the optical mode of the multimode fiber results in band splice performance, skew / jitter, and loss. Is improved. One way to improve link performance is to use multimode fiber using the pigtails of the single mode fiber of the optical transmitter module so that the center of the single mode fiber and the multimode fiber are offset by a predetermined offset. Is connected to the input side. This is referred to as an offset launch condition, which does not completely fill the multimode fiber, but only excites the annular mode, which propagates in the multimode fiber without appreciable attenuation. However, offset launch conditions that enhance the bandwidth performance of multimode optical fibers are difficult to achieve. This is because precise offsets cannot be consistently regenerated to produce the desired firing conditions.

For example, referring to FIG.
To receive a multi-mode fiber 142 including a core 144 having a radius of μm, the desired offset launch area 146 into the multi-mode fiber core 144 is about 13 μm to about 27 μm from the center of the multi-mode fiber core. Extend, which is about 17 μm to 23 μm core offset to launch a single mode fiber (8-9 μm in diameter). For a multimode fiber with a core radius of 25 μm, the desired launch area of the multimode fiber core is
From about 6 μm to about 2 from the center of the multimode fiber core
0 μm, which is a single mode fiber (diameter 8-9)
about 10 μm to 16 μm
A core offset of μm is obtained. For illustrative purposes, the core of the launching (or transmitting) single mode fiber 148 is shown at a location that launches offset into the multimode fiber 142. Thus, there is an offset launch area 146 in the multi-mode fiber core 144 where the single mode fiber on the transmitting side (i.e., launch side) is to be located where the optical signal is launched.

The offset launch V-groove adapter 150 according to the present invention, as shown in FIGS. 12 and 13, connects a first light guide having a single mode core 154 to a desired launch area of a multimode core 156 of a second light guide 158. Provides a vertical offset to be placed in. As shown in FIG.
60 is a predetermined distance 162 from the center axis 164 of the core 156.
Just offset. As discussed above, the offset firing region is the master V manufactured by the method described above.
It can be designed precisely using blocks. V
Since the groove is electroformed with a metal layer to form an insert for the injection mold, the offset firing V-groove adapter 150 can include a plastic V-groove portion that can be mass-produced and therefore less costly. It is advantageous.

Referring to FIGS. 14 and 15, offset firing V-groove adapter 170 provides a laterally offset firing. As shown, the first optical connector 1
The 74 single-mode core 172 has a central axis 176 laterally offset with respect to the central axis 178 of the multi-mode core 180 of the second optical connector 182. Offset 184 is
Forming a preform of the master V-block as discussed above allows for precise control. It is further recognized that the offset can be performed in both vertical and horizontal directions.

Many modifications and other embodiments of the present invention, having the advantages of the teachings set forth in the foregoing description and associated drawings, are contemplated by those skilled in the art. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are used herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[Brief description of the drawings]

FIG. 1A is a left perspective view of a V-groove adapter according to an embodiment of the present invention.

FIG. 1B is a right side perspective view of a V-groove adapter according to an embodiment of the present invention.

2A is a left perspective view of two light guides interconnected by the V-groove adapter shown in FIGS. 1A and 1B.

FIG. 2B is a right perspective view of two light guides interconnected by the V-groove adapter illustrated in FIGS. 1A and 1B.

FIG. 3 is a cutaway view of FIG. 2B taken along line 3′-3 ′;
FIG. 4B is a partial cross-sectional view of an interconnect between two light guides B.

FIG. 4 is a right side view of the V-groove adapter taken along line 4′-4 ′ of FIG. 2B, showing the axial alignment of the two light guides.

FIG. 5A shows the crystallographic structure of a V-groove etched in a (100) silicon substrate, viewed along the [01-1] direction.

FIG. 5B is a stereogram of a V-groove etched in a (100) silicon substrate, viewed along the [01-1] direction.

FIG. 6 is a schematic diagram of a light guide supported in a V-groove according to an embodiment of the present invention.

FIG. 7 is a schematic illustration of a light guide supported in a V-groove designed to place the center of the light guide in the same plane as the top surface of the V-groove.

FIG. 8 is a perspective view of a master V-block used to make a mold for a V-groove adapter according to an embodiment of the present invention.

FIG. 9 is a partial front cross-sectional view of an optical attenuator according to a particular embodiment of the present invention, wherein the cores of the light guides are offset by a predetermined amount to create a known loss in the interconnection of the two light guides. To do so, the two light guides are interconnected using a V-groove.

FIG. 10 is a partial front cross-sectional view of an optical attenuator according to a particular embodiment of the present invention, wherein the cores of the light guides are offset by a predetermined amount to create a known loss in the interconnection of the two light guides. To do so, the two light guides are interconnected using a V-groove.

FIG. 11 is a schematic diagram of a launch area of a multimode optical fiber for an offset launch condition.

FIG. 12 shows two connected using a V-groove adapter according to an embodiment of the present invention to create an offset firing condition.
FIG. 3 is a partial front cross-sectional view of the light guide of the book, where the offset is in the vertical direction.

FIG. 13 is a side view of the two light guides of FIG. 12 connected using a V-groove adapter according to an embodiment of the present invention to create an offset firing condition using a vertical offset.

FIG. 14 shows two connected using a V-groove adapter according to an embodiment of the present invention to create an offset firing state.
FIG. 3 is a partial top cross-sectional view of the light guide of the book, wherein the offset is in the lateral direction.

FIG. 15 is a side view of the two light guides of FIG. 14 connected using a V-groove adapter according to an embodiment of the present invention to create an offset firing using a lateral offset.

[Explanation of symbols]

 Reference Signs List 20 V-groove adapter 22 Larger V-groove 24 Smaller V-groove 25 Center axis 26 Structural member 28 Cross section 30 Reference facet 32 Bottom 36 Reference facet 46 First light guide 48 Second light guide 50 Core 51 Fixing mechanism 52 core 54 detent 56 spring guide 82 upper surface 84 silicon substrate 86 light guide 88 V groove 90 reference facet surface 91 upper surface 92 silicon substrate 94 contact point 96 bottom surface 102 master V block 104 silicon substrate 106 larger V groove 108 smaller one V-groove 110 Upper surface 120 V-groove attenuator 122 light conductor 124 core 126 light conductor 128 core 130 vertical offset 130 V-groove attenuator 132 light conductor 134 light conductor 136 offset 138 core 140 core 142 multi-mode fiber 144 core 146 offset launch area 148 single mode Fiber 150 Offset launch V-groove adapter 152 First optical conductor 154 core 156 Multimode core 158 Second optical guide 160 Center axis 162 Predetermined distance 164 Center axis 170 Offset launch V-groove adapter 180 172 Single mode core 174 First optical connector 176 center axis 178 center axis 180 multi-mode core 182 second optical connector 184 offset

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Muhammed A. Shahid United States of America 30078 Georgia, Snellville, Manoa Brook Court 2880 (72) Inventor Daniel El. Stephenson United States 30047 Georgia, Lilburn, Nimble Will Way 285

Claims (30)

[Claims] 1. An optical fiber adapter, comprising: a first alignment member defining a first V-groove adapted to internally support a first light guide, wherein the first light guide is a first light guide.
A second alignment member including a central axis and defining a second V-groove in proximity to the first V-groove and axially aligned, wherein the second V-groove supports a second light guide therein. Wherein the second optical waveguide includes a second central axis, and the first V-groove and the second V-groove have a coupling relationship including a predetermined degree of alignment between the first central axis and the second central axis. ,
Formed to support the first and second light guides;
Fiber optic adapter. 2. The first light guide having a first diameter and the second light guide having a second diameter, wherein the first diameter and the second diameter are different sizes. The optical adapter according to 1. 3. The optical adapter according to claim 1, wherein said predetermined alignment includes coaxial alignment between said first central axis and said second central axis. 4. The optical adapter according to claim 1, wherein the predetermined alignment includes an offset alignment between the first central axis and the second central axis. 5. The first V-groove has a first width,
The optical fiber adapter according to claim 1, wherein the second V-groove has a second width, wherein the first width and the second width are different. 6. The optical adapter according to claim 1, wherein said first V-groove has a valley cross section. 7. The first V-groove includes a third central axis, the second V-groove includes a fourth central axis, and the first V-groove and the second V-groove include the first and second central axes. The optical adapter of claim 1, wherein the optical adapter is formed to support the first and second light guides so as to be coaxial with the third and fourth central axes, respectively. 8. The first V-groove includes a third central axis, the second V-groove includes a fourth central axis, and the first V-groove and the second V-groove include the first and second central axes. The optical adapter of claim 1, wherein the optical adapter is formed to support the first and second light guides so as to axially align with the third and fourth central axes, respectively. 9. The optical adapter of claim 1, wherein the first light guide has a diameter of about 1250 micrometers and the second light guide has a diameter of about 2500 micrometers. 10. A method of making a mold for an optical fiber connector, comprising: a first V-groove having a first width in a monocrystalline material;
Forming a second V-groove of width, wherein the first V-groove and the second V-groove are in predetermined alignment with each other, further comprising: depositing metal in the first and second V-grooves; Forming a metal member having first and second V-groove concave engravings for use as a mold for forming an optical fiber adapter having aligned V-grooves. 11. The step of creating the first and second V-grooves includes creating the first and second V-grooves in a predetermined alignment including a coaxial alignment of the first and second V-grooves. The method of claim 10. 12. The step of creating the first and second V-grooves includes creating the first and second V-grooves in a predetermined alignment including an offset alignment between the first V-grooves and the second V-grooves. The method according to claim 10. 13. The method of claim 1, wherein forming the first and second V-grooves comprises forming first and second V-grooves that are larger than the resulting third and fourth V-grooves of the fiber optic adapter. Item 10. The method according to Item 10. 14. The method of claim 10, wherein creating the first and second V-grooves comprises creating the first and second V-grooves using photolithographic masking and etching techniques. 15. A method of making an optical fiber adapter, the method comprising: providing a mold defining a concave engraving of a first V-groove and a second V-groove, wherein the first and second V-grooves are adjacent to each other; Forming an adapter arranged in a predetermined alignment relationship and further having third and fourth V-grooves, each of the third and fourth V-grooves such that the individual light guides are in a predetermined axial alignment. And a method for supporting the light guide internally. 16. The step of forming a connector,
16. The method of claim 15, including forming the connector using injection molding. 17. The method of claim 17, wherein forming the adapter comprises:
The method of claim 15, comprising forming the adapter from plastic. 18. An optical fiber attenuator, comprising: a first alignment member defining a first V-groove having a first width, said first V-groove supporting a first optical waveguide therein. And a second alignment member that defines a second V-groove having a second width in proximity to the first alignment member, wherein the second V-groove is a second V-groove.
The first and second V-grooves are adapted to support the light guide therein, and the first and second V-grooves are mutually axially oriented so as to introduce a predetermined loss into an optical signal transmitted between the first and second light guides. An optical fiber attenuator supporting the first and second light guides in an offset alignment state. 19. The optical attenuator of claim 17, wherein said axial offset alignment is lateral. 20. The optical attenuator of claim 17, wherein said axial offset alignment is vertical. 21. The optical attenuator according to claim 17, wherein said first width and said second width are substantially equal. 22. The optical attenuator according to claim 17, wherein the first width and the second width are different. 23. The optical attenuator of claim 17, wherein the axial offset alignment is less than about 4 μm. 24. An optical fiber offset launch adapter for offset launching an optical signal from a single mode fiber to a multimode fiber, comprising: a first alignment member defining a first V-groove having a first width; The first V-groove adapted to internally support a first light guide having a multimode core, and further comprising a second alignment member defining a second V-groove having a second width; Are adapted to internally support a second light guide having a single-mode core, wherein the first V-groove is axially offset proximate to the second V-groove, and is thus offset from the single-mode core by the multi-mode core. An optical offset launch adapter wherein the optical signal emitted to the mode core does not completely fill the optical mode of the multimode core. 25. The optical offset launch adapter of claim 23, wherein the axial offset is lateral. 26. The optical offset launch adapter of claim 23, wherein the axial offset is vertical. 27. The optical offset launch adapter of claim 23, wherein said first width and said second width are substantially equal. 28. The optical offset launch adapter according to claim 23, wherein said first width and said second width are different. 29. The multimode core having a diameter of about 62.5 μm
24. The optical offset launch adapter of claim 23, wherein the axial offset is about 17-23 [mu] m. 30. The optical offset launch adapter of claim 23, wherein the multi-mode core is about 50 μm in diameter and has an axial offset of about 10-16 μm.